Personal Mercury Monitor for Exposure Measurements Project Summary/Abstract Workers in the oil and natural gas industry are vulnerable to exposure to toxic mercury (Hg) vapor as a result of routine inspection and maintenance of equipment such as compressors and other process equipment that concentrate species of low volatility over time. Exposure of workers to elemental mercury vapor is of concern in many other industries as well, including the chlor-alkali industry where mercury is used as an electrode, gold and silver mining where these precious metals are extracted with mercury, manufacture and recycling of fluorescent lamps, Super Fund site cleanup, dentistry, etc. As a result, there is a great need for a personal mercury monitor to protect the health of industrial workers. For the oil and gas industry, which is the largest potential market for a personal mercury monitor, there is an additional requirement that that the monitor be certified for operation in explosive atmospheres. Currently, no mercury monitor has the required ATEX (ATmosphres EXplosibles) certification for use in this industry where explosive atmospheres occasionally occur by accident. Also, for the oil and gas industry, the monitor must have high selectivity against other UV-absorbing species such as aromatic hydrocarbons (benzene, toluene, xylenes, etc.), which may be present at up to high ppm levels. In our Phase 1 work, we developed and launched the Hermes 1 Personal Mercury Monitor? as a product for measuring mercury vapor in the workplace. This pocket-sized instrument, which is based on atomic absorbance of the 254-nm emission line of a low pressure mercury lamp, measures mercury concentrations down to 0.1 ?g/m3 (compared to the OSHA 8-hr exposure limit of 100 ?g/m3) and achieves high selectivity against other UV-absorbing species by the innovative means of modulating the sample flow through a silver wool scrubber to selectively remove Hg by forming an amalgam. To the extent that aromatic hydrocarbons pass through the scrubber and are not modulated, they do not interfere with the measurement. The Hermes 1 may be used in nearly all industrial settings except for the oil and gas industry where explosive atmospheres may be encountered. Therefore, during the Phase 2 project we will redesign the mechanical and electronic components of the Hermes 1 to meet the requirements of ATEX Zone 1 certification. In Phase 2 we also will optimize the design of the silver scrubber to provide greater capacity for mercury removal and quantify selectivity factors for species likely to be found in the oil and gas atmospheric environment. The deliverable for this project will be the product launch of the Hermes 2 Personal Mercury Monitor?, which can be safely used in the oil and gas industry for personal monitoring of thousands of workers to protect from exposure to dangerous levels of this potent neurotoxin.